On rare occasions, aircraft slip out of control and overrun their runways, risking injury to passengers, destruction of adjacent property, and damage to the aircraft itself. Runway overruns can occur during take-offs or landings, with the aircraft leaving the runway at speeds of 70 knots or more. The Federal Aviation Administration (FAA) generally requires a runway safety area (RSA) of 1000 feet extending beyond the end of the runway. While RSA's have become an FAA standard, there remain many runways that were constructed prior to the adoption of the 1000 foot RSA standard. Many airports are located such that runways end adjacent to populated neighborhoods, roads and highways, water, or the like that cannot simply be moved to allow the construction of RSA's in compliance with the 1000 foot overrun requirement.
Shorter arrestor beds with tailored failure mode properties have become the common solution when longer RSA's are not possible. Several materials, including existing soil surfaces beyond the runway have limited abilities to decelerate aircraft. Soil surfaces, while cheap, are very unpredictable in their arresting capability because their properties are quite variable, arising both from soil type and ambient weather and climate conditions. Very dry clay can be hard, slick and nearly impenetrable, while wet mud can cause aircraft to bog down too quickly and damage the landing gear during slowdown. Porous cement offers some advantages, but is still tougher than optimal for slowing aircraft. Other proposed materials are compressible or have a compressible failure mode, which is largely undesirable for arrestor bed use.
Thus, there remains a need for an easily produced arrestor bed material that is heat and chemically resistant and fails with a predictable and predetermined crushing mode to controlledly slow down oncoming aircraft. The present invention addresses this need.